1. Field of the Invention
The present invention relates to a digital broadcasting system and a technology used for a receiving apparatus in the system, particularly relates to a signal processing technology which controls the receiving apparatus or a device connected to the receiving apparatus according to an audio signal included in a broadcast wave.
2. Description of the Related Art
Digitization of television broadcasting such as BS digital broadcasting and terrestrial digital broadcasting begins in earnest. In such services of the digital broadcasting, there is data broadcasting which enables a bi-directional service with a receiving user. The data broadcasting is described in “Data broadcasting encoding method and transmission method in digital broadcasting” which is of a standard specification by Association of Radio Industries and Businesses (ARIB).
In the data broadcasting, there is an event message transmission method. In the event message transmission method, message information is sent from a broadcasting station to an application running on a receiving apparatus, and the message information triggers the receiving apparatus to perform a designated operation. For example, a graphic can be multiply-displayed in a program image displayed on a screen connected to the receiving apparatus in synchronization with a showing program, or a data recording apparatus such as D-VHS, a hard disk recorder, and DVC (Digital Video Camera) can be controlled to record program contents, or a printer can be controlled to print the program contents.
Then, a system on the sending side and a data receiving portion and a data restructuring portion on the reception side in the conventional digital broadcasting will be described with reference to FIG. 11 and FIG. 12.
An AV (Audio Visual) contents encoding apparatus 1001 reads data from a VTR device in which video contents data and audio contents data are recorded. The AV contents encoding apparatus 1001 performs compression such as MPEG2 and coding to generate an elementary stream (hereinafter, referred to as ES) including the coded image and audio, and the AV contents encoding apparatus 1001 outputs ES to an AV contents generating/sending apparatus 1002.
The AV contents generating/sending apparatus 1002 synchronizes ES of the image and ES of the audio which are outputted from the AV contents encoding apparatus 1001, and the AV contents generating/sending apparatus 1002 outputs the data to a multiplexer 1009.
A data contents generating apparatus 1003 produces data-broadcasting contents including mono-media data such as BML data, PNG, and JPEG data to form section data, and the data contents generating apparatus 1003 outputs the section data to a data contents sending apparatus 1004.
The data contents sending apparatus 1004 forms a data carousel of a data from the data contents generating apparatus 1003 according to a predetermined sending schedule, and the data contents sending apparatus 1004 sends the data carousel to a multiplexer 1009.
An event message generating apparatus 1005 produces stream descriptors including a general-purpose event message descriptor and a NPT (Normal Play Time) reference descriptor to form the section data, and event message generating apparatus 1005 outputs the section data to an event message sending apparatus 1006.
The data from the event message generating apparatus 1005 is outputted to the multiplexer 1009 with a predetermined sending schedule or at arbitrary timing of an apparatus operator by the event message sending apparatus 1006.
A program information generating apparatus 1007 forms the section data of information on a broadcasting program schedule including EIT (Event Information Table), and the program information generating apparatus 1007 outputs the section data to a program information sending apparatus 1008.
The data from the program information generating apparatus 1007 is outputted to the multiplexer 1009 at predetermined sending timing by the program information sending apparatus 1008.
The multiplexer 1009 generates a transport stream (hereinafter, referred to as TS) by packetizing and multiplexing the stream and the data from the AV contents generating/sending apparatus 1002, the data contents sending apparatus 1004, and the event message sending apparatus 1006, and then the multiplexer 1009 outputs TS to a post-stage digital modulator (not shown).
FIG. 12 is an explanatory view in the case where the image data, the audio data, and the data-broadcasting data are extracted from TS, which is received and demodulated through an antenna and a tuner (not shown) by a demultiplexer 1110, in a conventional digital-broadcasting receiving apparatus.
Referring to FIG. 12, reference numeral 1101 denotes TS in which the pieces of video data, audio data, SI data constituting an electronic program guide (EPG), and data-broadcasting data of plural channels exist in a time division multiplexed manner.
TS is formed in packet (TS packet) unit having a certain size. PID (Packet Identifier) which is of an identifier for identifying a type of data included in the TS packet is given to a header portion 1102 of each TS packet. Table ID which depends on the type of data is given to each of PSI data 1107, SI data 1109, and data-broadcasting data 1108, which are divided in a payload portion 1103 of the TS packet. A section filter 1112 takes the pieces of data of the PSI (Program Specific Information) data 1107, the SI (Service Information) data 1109, and the data-broadcasting data 1108 based on the Table ID, and section filter 1112 sends the data to a data stream processing unit 1106.
When the video data and the audio data are taken out, in a demultiplexer 1110, first the PSI data 1107 existing in the payload portion 1103 of the predetermined TS packet is taken out with a PID filter 1111 and a section filter 1112, and the PSI data 1107 is sent to the data stream processing unit 1106. The PSI 1107 defines the contents of the whole of TS 1101. After a process of analyzing the PSI data 1107, the demultiplexer 1110 takes out the video data and the audio data using the pieces of information on the analyzing process, and the demultiplexer 1110 outputs the video data and the audio data to a video decoder 1104 and an audio decoder 1105.
Then, the data-broadcasting data 1108 will be described. The data-broadcasting data 1108 are mainly divided into (1) DII (Download Info Indication) transmitted by a data carousel transmission method, (2) DDB (Download Data Block), and (3) An event message (stream descriptor) transmitted by an event message transmission method.
(1) DII is the section data for describing a transmission parameter of a data broadcasting contents module including the mono-media data such as the BML data, PNG, and JPEG and the attribute information of each module.
(2) DDB is the section data in which the module is divided into blocks having certain sizes.
(3) The event message (stream descriptor) is used in synchronous and asynchronous message notification for receiving apparatus application by combining the event message with DII and DDB which are transmitted by the data carousel transmission method, and the event message is the section data including the general-purpose event message descriptor and the NPT reference descriptor as described above.
In the receiving apparatus, while the data broadcasting service is received and displayed, the BML contents and the event messages designated by a broadcasting station are always received at the same time with the PID filter 1011 and the section filter 1112, a predetermined control operation is performed by the type of the event message taken and divided.
Japanese Patent Application Laid-Open No. 63-190438 discloses a configuration in which the control is performed by sending the audio signal while the audio signal is mixed with a low-frequency control signal such that a commercial message is not recorded in VTR.
The V-chip is a well known method for previously preventing an underage person from watching a harmful image (refer to Japanese Patent Application Laid-Open No. 11-317913). In the method, the dedicated V-chip installed in a television and so on reads rated data (attribute information such as “adult program” and “parental guidance suggested”) added to the contents to determine whether the contents can be displayed or not.